Alzheimer's disease is a daunting diagnosis. But working closely with your health care team to find the best strategies to manage your symptoms can help you cope and make life better.

Alzheimer's drugs offer one strategy to help manage memory loss, thinking and reasoning problems, and day-to-day function. Unfortunately, Alzheimer's drugs don't work for everyone, and they can't cure the disease or stop its progression. Over time, their effects wear off.

Research into more-effective Alzheimer's drugs is ongoing. But even if researchers discover better drugs, it will always be important to build a health care team that helps you explore all your treatment options. That may involve taking medication, tapping into your support network, and accessing community resources and services.

The Food and Drug Administration (FDA) has approved two types of drugs specifically to treat symptoms of Alzheimer's disease.

Cholinesterase inhibitors

Memantine

These drugs:

Work in two different brain chemical messaging systems. Because of this, doctors sometimes prescribe both types at the same time. More research is needed, though, to understand how great the benefit might be from taking both categories of drugs together. Future drugs may target the disease through other strategies.

Are approved for specific Alzheimer's stages. These stages — mild, moderate and severe — are based on scores on mental-function tests that assess memory, awareness of time and place, and thinking and reasoning.

Doctors may, however, prescribe Alzheimer's drugs for stages other than those for which the FDA has approved them. Doctors do this because Alzheimer's stages are not exact, individual responses to drugs may vary, and current treatment options are limited.

If your doctor prescribes medication as part of your Alzheimer's care plan, make sure you understand the drug's potential benefits and risks for your situation.

Are not approved for mild cognitive impairment (MCI). This condition, which involves subtle changes in memory and thinking, may sometimes be a transitional stage between normal age-related memory changes and Alzheimer's disease. Many people with MCI — but not all — eventually develop Alzheimer's.

Clinical trials testing whether Alzheimer's drugs might prevent progression of MCI to Alzheimer's have generally shown no lasting benefit. However, some prescribers do elect to try cholinesterase inhibitors in the MCI stage.

One way Alzheimer's harms the brain is by decreasing levels of acetylcholine, a chemical messenger that's important for alertness, memory, thought and judgment. Cholinesterase (ko-lin-ES-tur-ays) inhibitors are a type of drug that boosts the amount of acetylcholine available to nerve cells by preventing its breakdown in the brain.

Cholinesterase inhibitors can't reverse Alzheimer's disease, and they don't stop the underlying destruction of nerve cells. Because dwindling brain cells produce less acetylcholine as the disease progresses, these medications eventually lose effectiveness.

There are three FDA-approved cholinesterase inhibitors. In clinical studies, all cholinesterase inhibitors, on average, work about equally well. But in individuals, one cholinesterase inhibitor may work better or produce fewer side effects than does another.

Common side effects can include nausea, vomiting and diarrhea. Starting treatment at a low dose and working up to a higher dose can help reduce side effects. Taking these medications with food also may help minimize side effects.

Three cholinesterase inhibitors are commonly prescribed:

Donepezil (Aricept) is the only Alzheimer's drug approved to treat all stages of the disease. It's taken once a day as a pill. It's usually well-tolerated, with side effects occurring in about 20 percent of people who take it.

Galantamine (Razadyne) is approved to treat mild to moderate Alzheimer's. It's taken as a pill or syrup. Some trials showed that galantamine slowed cognitive decline in people with Alzheimer's. These benefits lasted up to 36 months.

Rivastigmine (Exelon) is approved for mild to moderate Alzheimer's disease. It's taken as a pill or syrup. It's also available as a drug-releasing skin patch. The effectiveness of rivastigmine appears to be comparable to donepezil, although it may have more gastrointestinal side effects.

Memantine (Namenda) is approved by the FDA for treatment of moderate to severe Alzheimer's disease. It works by regulating the activity of glutamate, a messenger chemical widely involved in brain functions — including learning and memory. It's taken as a pill or syrup. Common side effects include dizziness, headache, confusion and agitation.

Since memantine's original approval for moderate to severe Alzheimer's, researchers have conducted additional studies to determine whether memantine might also help in earlier stages. But none of this additional work shows that memantine has any benefit for mild Alzheimer's disease.

Because Alzheimer's is a progressive disease, your symptoms and care plan will change over time. If you're taking an Alzheimer's drug, ongoing review of your care plan will include working with your doctor to decide how long you should continue your medication.

It may be difficult to tell if Alzheimer's drugs are helping, because their effect is usually modest. On the other hand, it's hard to know how severe your symptoms might be without your medication.

If you stop taking an Alzheimer's drug and experience a sharp decline in your condition, contact your doctor. He or she may advise restarting the medication.

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